Commercial gains

Domestication and selective breeding have been used for millennia to enhance harvest yield and quality in livestock farming and horticulture, but it is only in recent years that this method has been applied to shellfish.

One of the big advantages of seafood crop domestication is the ability to make commercial gains from selective breeding. Our selective breeding programmes have resulted in yield gains of up to 20% per generation for mussels and oysters.

Selective breeding

Selective breeding of shellfish is a big undertaking. A large number of animals are involved, each individual needs to be identifiable, and each generation goes through all stages of the complex shellfish life cycle, including the growing-out period under typical farm conditions.

Some of the pitfalls are of a scientific nature (e.g. inbreeding), while other practical issues can be solved by good collaboration with industry.

Breeding programmes

Cawthron has established selective breeding programmes for the Pacific oyster and Greenshell™ mussel. Much of this expertise is transferable to the selective breeding of other broadcast-spawning invertebrates, be it marine or freshwater species.

Breeding programmes for the Flat oyster and geoduck are now also underway.

Our breeding programmes are based on established principles of quantitative genetics. Production gain is optimised through sound science.

Family production

A 'family' is the offspring from two known parents. Each family may consist of several thousand siblings grown together until they are large enough for transfer to the farm. About 50 to 60 families per cohort are needed to establish an effective breeding programme.

The generation-cycle of mussels and oysters is typically two years. During this time, a wide range of individual steps are executed to complete a successful generation.

Cryopreservation of eggs, sperm and embryos

Cawthron is developing methods for the cryopreservation of sperm, eggs and larvae of shellfish, which goes hand-in-hand with selective breeding, such as those programmes already in place for the Greenshell™ mussel and the Pacific oyster.

Cryopreservation is the storage of live material at temperatures so low that all biological processes are suspended (-196 °C). Cryopreservation enables the storage of sperm and eggs from superior stock and the creation of new offspring at will, without having to worry about conditioning the adults or ensuring that particular individuals are spawned at the same time.

The sperm and eggs can be stored beyond the lifespan of the parent, so crosses that would not normally be possible, can be made in the future.

Cryopreservation also enables hatcheries to produce juveniles (spat) year-round, without the costs of having to bring broodstock into spawning condition out of season.

Health management for fish, shellfish and other aquatic animals and plants

Higher value species development

Research is underway to support the development of two new commercial aquaculture species – the Flat oyster and geoduck. In addition to Cawthron's work on developing breeding programmes for these species, a number of different farming systems are being investigated. This work is being undertaken in conjunction with industry partners.

Land-based aquaculture of shellfish and finfish

Land-based aquaculture systems provide an alternative to inshore waters, and enable increased production of a whole range of species through improved control over growing conditions, feeding and biosecurity.

Cawthron has developed a land-based aquaculture site selection tool (LBASS) to find New Zealand's best sites for land-based aquaculture.

Rather than evaluating a limited shortlist of identified sites, users of LBASS (a GIS-based tool ) can search across an entire region for previously unidentified sites that meet the criteria derived from the specific needs of a land-based aquaculture proposal.